Despite archival biological specimens record ecological information in their tissues in the form of stable isotope ratios, there was a difficulty with estimating past food web properties because of lack of isotopic information on trophic baseline. Recently, δ¹⁵N of amino acid (δ¹⁵N _AA) is regarded as a useful tool to estimate the precise trophic levels (TLs) of consumers. To reconstruct the long-term tropho-dynamics of a predatory fish (Opsariichtys uncirostris) in Lake Biwa, we analyzed δ¹⁵N of glutamic acid and phenylalanine (δ¹⁵N _Glu and δ¹⁵N _Phe) of its archival specimens collected from 1914 to the present. To chronologically calibrate the past aquatic food base on which δ¹⁵N _Phe was more enriched with eutrophication, we also measured δ¹⁵N _Phe for archival specimens of a pelagic fish Gymnogobius isaza which relies on aquatic food sources exclusively. The source mixing models of aquatic and terrestrial food sources revealed that the predator TLs increased in 1970s and then decreased in 1990s.Their TLs were strongly correlated with those estimated from their bulk δ¹⁵N, suggesting that the δ¹⁵N _AA analysis of archival specimens is a promising approach to reconstruct the long-term changes in food web properties in lake ecosystem.